The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Vehicles can include an internal combustion engine that generates drive torque to drive wheels. More specifically, the engine draws in air and mixes the air with fuel to form combustion mixtures. The combustion mixtures are compressed within cylinders and are combusted to drive pistons that are disposed within respective cylinders. The pistons rotatably drive a crankshaft to transfer drive torque to a driveline and ultimately to the wheels.
Modern engine control systems are designed to minimize exhaust emissions while maximizing power and fuel economy. Advancements in spark timing for a given air/fuel ratio are made to increase power and improve fuel economy. In general, advancing the spark relative to top dead center increases torque until a point is reached at which best torque is produced. Abnormal combustion, also known as engine knock, occurs when the spark is advanced too far. The temperature and pressure of the unburned air/fuel mixture exceeds a critical level causing the gases to auto ignite. This combustion produces a shock wave that generates a rapid increase in cylinder pressure. Damage to pistons, rings, and exhaust valves can result if sustained heavy knock occurs. Additionally, most people find the sound of heavy engine knock undesirable.
Conventional knock detection systems include a knock sensor and a dedicated knock detection chip (knock IC) to process the knock sensor signal and calculate the engine knock intensity. An individual knock sensor and knock IC can be used to detect knock from each cylinder. Conventional knock reduction systems detect knock during certain drive conditions and retard spark. The retardation of spark occurs regardless of changed drive conditions. This results in suboptimal engine performance and fuel consumption.